1. Field of the Invention
The present invention relates generally to a golf club having a vibration damping device and method for making same and, more specifically, to a light weight golf club having a flexible vibration damping device incorporated therein and a method for making same which damps vibrations over a broad range of frequencies.
2. Description of the Related Art
In the game of golf, a club is used to strike a stationary ball, driving it along a course with the object of placing the ball in a hole in the shortest number of strokes. Golf clubs come in a number of varieties, most prominently distinguished by the shape of the head. A shaft is attached at one end to the head and typically includes a grip at the opposite end of the shaft. Club heads may be generally categorized as "woods," "irons," and "putters" as is commonly known in the art. The impact of the ball on the hitting surface or face of the club generates vibratory phenomena on the shaft of the club. When the ball is hit perfectly, this vibratory phenomena is not objectionable to the player and may even be pleasant, creating a distinctive sound indicating that the ball was well struck in the "sweet spot" of the club face.
On the other hand, when the ball is not hit perfectly at dead center of the "sweet spot" on the club face, torsional and bending forces are introduced to the club. These forces result in unfavorable vibratory phenomena having multiple resonant frequencies to 5,000 Hz and sometimes higher. These vibrations are transmitted to the golfer through his/her hands and can be very unpleasant. Such unpleasant experiences can have a negative effect on the players and thereby decrease the enjoyment of the game of golf.
There have been numerous attempts to address and reduce the above problem. For example, one attempt to address the above problem has been to provide vibration damping devices which are designed to specific type of modes of vibration over a limited frequency range. Such vibration damping devices rely on the constrained layer damping principle wherein a viscoelastic material is disposed between a stiff, rigid plate or member and the shaft to be damped. Vibrations cause the stiff, rigid plate or member to move relative to the shaft which causes shear in the viscoelastic material. However, such devices suffer from the disadvantage that they are limited to damping only those modes of vibration which have their high modal strain energies at the location of the device and are not suitable for reducing unwanted vibration over wide frequency ranges such as encountered by the ball impact on the golf club. Also, such devices are limited in their application to golf clubs due to the added weight of the rigid member. More specifically, the number of modes of the vibration generated in the golf club is a function of the length of the shaft, among other things. In order to damp most of the undesirable modes that may be created in a golf club, the rigid member must be employed over a substantial portion of the length of the shaft which is unacceptable due to the weight added to the club shaft by the use of the rigid member. Thus, there is a need in the art for a vibration damping device which is light weight, inexpensive and yet can damp resonant vibrations over wide frequency ranges.